The club's finances have been in doubt since owner Carson Yeung was arrested in Hong Kong last month and charged with five counts of money laundering.
Yeung, who denies the charges, has seen his assets frozen and shares in the club's holding company have been suspended.
Pannu admits the Championship club may be forced to sell their best players, including Scott Dann, Ben Foster and Liam Ridgewell to ensure they can pay their bills.
"Upon my return I may have to make some unpopular decisions and I hope the fans will understand that I effectively don't have a choice," Pannu told the Daily Mirror.
"The club may need to do what is right and to buy time until Carson's assets are dislodged from the clutches of the courts in Hong Kong."
Pannu is hopeful Birmingham International Holdings Limited would soon be able to meet the demands of its bankers, HSBC, and that trading in shares would resume, but could not offer guarantees of how the club would continue to fund itself in the meantime.
"An update to the fans is long overdue and it is just fair they hear the latest developments from me now," added Pannu.
"But I am not aware of their plans as to how they propose to fulfil the financial distress posed by the relegation scenario and the freezing of Carson's assets in Hong Kong.
"Carson had been trying hard to find new investors but the money laundering charges understandably meant that the progress had been slow. "